The animal came after the a 36-year-old attorney from Toledo, Ohio, in clear blue waters in an area not known for shark attacks. The last such incident in that area dates back almost 50 years, the state's Shark Task Force said.
The father of four was snorkeling and looking for turtles about 150 yards from shore when he noticed that fish near him looked spooked.
Then he saw a large shark's flat snout and felt the animal spin him around.
Speaking to reporters at The Queen's Medical Center in Honolulu, where he was taken after the attack, Miller said he punched the shark twice right below its dorsal fin, scaring it away.
Then Miller started screaming and yelling for help and headed for shore.
A day later, he was sitting in a hospital wheelchair, tired and nauseous from the pain medicine but grateful for his doctor's estimate that he should be walking in a few months and hopefully playing basketball with his teenage son in a half-year to a year.
"I'm happy _ one, to be alive and two that I don't anticipate ... losing the leg," he said.
Miller said a stranger helped save him by wading into the ocean to answer his cries for help.
"He's my hero. I would not have made it out of the water without his assistance. I owe my life to that man," Miller said.
Dr. Patrick Murray said the shark came down on Miller's leg and knee with "tremendous" force.
